Integrated circuit dies must be tested before they are packaged. Often, integrated circuit dies are defective and it is highly undesirable to package defective dies as packaging often represents an expensive step in the manufacture of integrated circuits.
Probe cards are commonly used in the art of testing integrated circuits dies. Probe cards consist of a flat rigid plate with probes arranged radially on the surface of the plate. The central portions of the probes have tips which are positioned to be aligned with contact pads on a top surface of the integrated circuit die. The probe tips must be accurately aligned so that contact is made with all the contact pads on the integrated circuit die. A typical die may have a dozen or more contact pads.
Another concern in the manufacture and use of probe cards is the planarity of the probe tips. It is desirable when contacting integrated circuit dies to have similar contact forces between all the contact pads and probe tips. Since the top surface of the die and the contact pads are planar, the probe tips must also be planar (and planar parallel to the die top surface) so that the contact forces on the contact pads are the same. Maintenance of probe tip planarity is a very important consideration in the manufacture and use of probe cards.
Presently, many integrated circuit manufacturers are testing integrated circuit dies at elevated temperatures to satisfy military specification requirements. Typically, dies must be tested at temperatures of 125.degree. C. Of course, the probe card must be contacted to the die while the die is at an elevated temperature. The means for heating the die will typically also heat the probe card used to test the die. Therefore, a probe card to be used for testing dies at elevated temperatures must maintain probe tip planarity and alignment at elevated probe card temperatures. Conventional epoxy printed circuit board probe cards soften at high temperatures and so do not maintain adequate probe tip planarity and alignment.
Therefore, it would be an advance in the art of integrated circuit die testing to provide a probe card capable of maintaining probe tip planarity and alignment at elevated temperatures. It would also be an advance in the art to provide a probe card that has increased rigidity at room temperature.